Medical device designers are a little uncertain about how to approach the ever-growing trend of wearable technologies. There’s no question that they can be useful, but exactly
how and where they might present a consistent solution in
the healthcare industry has been the subject of much scrutiny. “As the lines between “fitness,” “wellness,” and “medical”
wearables become more blurred, and companies like FitBit
and Misfit shift towards the health monitoring space, there is
mounting pressure for wearables to be even more accurate,”
said Mike Salas, Ambiq Micro’s VP of Marketing in response
to the question of what to expect for medical device design in
2016, featured in last month’s issue of MDT.

Attempts to find usefulness for medical wearables reflects
the goal for healthcare to move toward smaller, smarter,
and less intrusive technologies: designing devices in this way
makes the jobs of patient and practitioner alike much easier.
But as they’re still an adolescent technology, researchers are
still working out some of the kinks.

Power Struggle

Arguably the largest hurdle to overcome in designing an effective
medical wearable is how to power it. Presumably, the device
is going to be on all the time and making continuous analyses
or otherwise in a “low-power” mode while not doing its work.

Plugging it into the wall for power defeats the purpose of even
making the device wearable, so it’s all down to the battery
design. A medical wearable’s battery must be powerful enough
to hold a charge for at least a few days (depending on the type
of continuous monitoring needed) and have a speedy recharge
time.

Or, perhaps the power source itself should also be wearable!
Thinking along these lines, Case Western Reserve University
researchers have created flexible, wire-shaped microsuperca-pacitors that are meant to be woven into a jacket, shirt or dress.

The capacitors can be customized to match charge storage and
delivery requirements of any worn devices by either design or
connection in series or parallel.

The new supercapacitor touts a titanium wire coated withpolyvinyl alcohol and phosphoric acid, combined to form a sol-id electrolyte. The second electrode is formed by wrapping thetitanium wire with yarn or a sheet of aligned carbon nanotubes.The semiconducting titanium dioxide nanotubes prevent shortcircuiting by separating the two active parts of the electrodes.Capacitors provide an alternative to batteries by virtue ofcharging and releasing energy much more quickly—which med-ical wearables will definitely need.

It helps to have a flexible power source so any deforming
that occurs doesn’t affect the capacitor’s output. The supercapacitors were bent up to 180 degrees hundreds of times without demonstrating loss of performance. “They’re very flexible,
so they can be integrated into fabric or textile materials,” said
Liming Dai, the Kent Hale Smith Professor of Macromolecular
Science and Engineering. “They can be a wearable, flexible
power source for wearable electronics and also for self-powered biosensors or other biomedical devices, particularly for
applications inside the body.”